Paraffin, one of the important thermal energy storage materials, possesses various desirable characteristics (e.g. high heat of fusion, variable phase change temperature, self-nucleating, no phase segregation and low cost), but has low thermal stability and is flammable. In the current study, form-stable phase change materials (PCMs) based on EPDM (supported material), paraffin (dispersed phase change material), nano structured magnesium hydroxide (nano-MH) and red phosphorus (RP) with various compositions were prepared. The self-synthesized nano-MH has a kind of lamellar structure with good dispersal as characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The constructional morphology, thermal stability, latent heat and flame retardant properties of as-prepared form-stable PCM blends were evaluated by using a scanning electron microscope (SEM). thermogravimetric analysis (TGA), a differential scanning calorimeter (DSC) and limited oxygen index (LOI) tester, respectively. The SEM and DSC results show that addition of nano-MH and RP has no apparent negative effect on EPDM/paraffin three dimensional netted structures and latent heat. The TGA curves indicate that inducing the nano-MH into the form-stable PCM blends leads to the reinforcement of thermal stability, increasing the amount of char residuals at 700 degrees C thereby improving the flame retarding performance. (C) 2010 Elsevier Ltd. All rights reserved.